262 PLANT-BREEDING 



time as possible. Varieties with larger seeds are therefore 

 preferable by far, since they do not contain the aberrant 

 little ones, which are the chief cause of the loss and of the 

 trouble. 



At the Swedish agricultural experiment station at Svalof 

 another method has been developed to get rid of this nui- 

 sance. Though it is not directly related to our main subject, 

 it is as well to dwell upon it here, for a short time. It has 

 been discovered that with clover and other leguminous forage 

 crops the whole question of the sluggishness of the germinat- 

 ing process is due to the resistance of the outermost layer 

 of the seed coats to the absorption of water. Small seeds 

 of clover remain absolutely dry in water for days and weeks, 

 and in this condition they may even be thrown into boiling 

 water without being killed. It is the very thin cuticle of 

 their epidermis which impedes the penetrating of the water 

 into the inner parts and thus prevents the initiation of that 

 process of saturation w^hich is the necessary condition of all 

 germination. If there were only a small hole, or a small 

 non-resistant spot, the water might pass by this and effect 

 a complete imbibition. On this principle the Svalof method 

 is based. It allows of fiUng all the seeds on a small spot, 

 making their coats locally permeable for water, without 

 changing them in any other way. In order to do tliis, an 

 apparatus has been built, which throws the seed against a 

 filing disk in an obUque direction and in continuous current. 

 Thereby the culture of many species of leguminous plants 

 has been made possible and advantageous, which formerly 

 were disregarded on account of their imperfect germination. 

 By this means the selection of larger seeds and the applica- 

 tion of this part of the principle of correlation is made super- 

 fluous. 



My second point is the value of rapidly germinating 

 seeds in all cases where the germination period is the time 



